Summary of Significant Accounting Policies - Adoption of Topic 606 and ASC 842, Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue: Customer agreements and incentives	$ 66,990	$ 49,090
Cost of customer agreements and incentives	54,576	42,613
Sales and marketing	44,079	33,132
General and administrative	32,893	24,608
Interest expense, net	28,198	20,558
Income tax expense	8,203	5,400
Net loss	(91,420)	(75,155)
Net loss attributable to noncontrolling interests and redeemable noncontrolling interests	(119,452)	(85,037)
Net income available to common stockholders	$ 28,032	$ 9,882
Basic (in dollars per share)	$ 0.26	$ 0.09
Diluted (in dollars per share)	$ 0.25	$ 0.09
Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue: Customer agreements and incentives		$ 48,098
Cost of customer agreements and incentives		44,336
Sales and marketing		31,676
General and administrative		24,621
Interest expense, net		15,277
Income tax expense		7,338
Net loss		(73,084)
Net loss attributable to noncontrolling interests and redeemable noncontrolling interests		(85,811)
Net income available to common stockholders		$ 12,727
Basic (in dollars per share)		$ 0.12
Diluted (in dollars per share)		$ 0.12
Adoption Impact | Accounting Standards Update 2014-09 and ASC 842
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue: Customer agreements and incentives		$ 992
Cost of customer agreements and incentives		(1,723)
Sales and marketing		1,456
General and administrative		(13)
Interest expense, net		5,281
Income tax expense		(1,938)
Net loss		(2,071)
Net loss attributable to noncontrolling interests and redeemable noncontrolling interests		774
Net income available to common stockholders		$ (2,845)
Basic (in dollars per share)		$ (0.03)
Diluted (in dollars per share)		$ (0.03)